Process for the wet sealing of concrete pavers and the stabilization of inter-paver sand filled joints using non-solvent based water soluble acrylic emulsion sealant

ABSTRACT

An application process for an environmentally friendly water soluble acrylic emulsion paver sealant. The process described herein supports environmentally friendly application, a cost effective application that can be completed in 1 day without the normal “drying time” of other sealants and other application processes. The process stated herein is not sensitive to moisture as with other sealants. The sealant can be applied under wet or dry conditions and provides deep sealing with the application of a flood coat. The ability to apply a flood coat of sealant under wet or dry conditions speeds the application of the sealant and results in the elimination of the normally necessary “drying time” required in the application of other sealants. Furthermore, the application of a flood coat under wet conditions minimizes the formation of effervescence. 
     The described process herein further supports a host of sealant additives to improve the environmental characteristics of the sealant. Anti-algaecide and anti-fungicide additives retard the growth of mold, mildew and moss on the pavers. Another sealant additive retards the propensity for tire marking when pavers are used in areas of vehicular traffic. 
     The process further supports a surface enhancement that results in improved surface luster, making the pavers more visually appealing. 
     The unique and novel process has been developed in conjunction with a specially formulated water soluble acrylic emulsion sealant compatible with this wet application process that provides paver sealing, sand joint stabilization, and visual surface enhancement.

BACKGROUND

1. Filed of the Invention

It has long been known that patio, sidewalk and driveway pavers were subject to physical and visual degradation and ultimate failure over time due to various environmental factors. Environmental factors such as sunlight, rain, snow, freezing and biological factors such as fungus, moss, mold and mildew over time can degrade the structure and physical appearance of pavers. Numerous techniques have been developed over the years to protect pavers from such adverse attacks. The need for paver protection is increasing, especially in recent years. Between 1998 and 2004 concrete paver installed square footage has grown from 251 million square feet to 630 million square feet.

This patent application describes a method for the application of a specific water soluble and environmentally friendly acrylic emulsion sealant using an application process that speeds application, reduces the release of Volatile Organic Components (VOC's), enhances surface finish, locks in and stabilizes joint filler sand, and reduces the likelihood of application call backs. The inventive sealer application process described herein has been optimized for a specific type of acrylic emulsion sealant recently developed in conjunction with the testing and trials of the inventor/applicant. This process minimizes the number of steps and time necessary to achieve the desired results of: an attractive physical appearance (surface enhancement), providing suitable sealing against environmental degradation and allows for installation and application in a fraction of the time of other prior art sealant application processes. The claimed process typically allows the job to be completed in 1 day rather than multiple days using other application processes and sealant chemistries.

2. Description of Prior Art

There are two types of sealers that are used to protect and add luster to concrete pavers. The penetrating sealer contains silicates that form a bond with the capillary structure of the concrete. The penetrating sealer protects the paver from water penetration without changing the surface appearance, hence provides no surface enhancement.

The film sealer is most used for decorative concrete sealing. Three major types of film sealers are available. The first being Acrylics that are available in both solvent and water based formulations. The second type, Polyurethane sealers are also available in water and solvent based varieties. Polyurethane sealers are moisture intolerant until they cure. Any moisture in the paver during application of the sealer or during the curing process will result in bubbling, that ruins the finish and visual appearance of the application. Urethane sealers are typically not UV tolerant, hence are normally restricted to indoor applications. The third type of sealer is the Epoxy sealer. Epoxy sealers are not tolerant to ultraviolet light, hence are not typically used for outdoor paver sealing applications and typically do not allow the paver to release moisture, hence may lead to premature sealer failure or paver structural failure over time.

Both Epoxy or Urethane sealer application can result in trapped moisture in the paver that may ultimately result in a loss of “sealer to paver surface bond” indicative of pealing or flaking failures. Both of these sealants require the use of sand blasting or strong chemical strippers (methylene chloride and others) to remove the failed sealant surface prior to reapplication. Prior art references such as the Interlocking Concrete Pavement Institute Tech Spec Number 5, ©1995 revised 2001 describe prior art sealing products and their characteristics.

Another type of product the “cure and seal” is used on new concrete that has not undergone a full cure. Cure and seal acrylic resins are not well suited for fully cured concrete paver sealing.

For exterior concrete paver sealing applications, solvent based sealers are generally used. Solvent based acrylic sealers became popular for reasons of durability, ultraviolet radiation resistance, surface finish and the ability to allow moisture to evaporate through the paver. Epoxy and Urethane concrete sealers are not ultraviolet radiation resistant on their own and UV inhibitors must be added, they do not pass moisture well and are typically more expensive than solvent based acrylics making them less desirable for large exterior applications.

Solvent based sealers, contain environmentally damaging chemicals. Typical solvent based sealers contain Toluene, Xylene, Trimethylbenzenes and other potentially hazardous chemicals. Solvent based sealants containing such chemicals can and do upon application evaporate into the atmosphere. Manufacturer Safety Data Sheets (MSDS) specifically mention safety concerns for such products. Federal Guidelines for Volatile Organic Components (VOC's) require sealer application under specific conditions and normally prohibits the use of thinners. An additional fire risk factor is the elevated paver surface temperatures due to direct sunlight exposure of the paver that are normally encountered during the application process. Elevated surface temperatures increase evaporation and increase the possibility of fire due to rapid volatilization of the solvent contained in the sealer.

The clean up of such solvent based sealers, again requires the use of VOC's such as lacquer thinner, toluol, or xylol. These clean up chemicals are dangerous to the environment and to the person performing the clean up activity.

The water based acrylic sealants used to protect pavers are more environmentally friendly than their solvent based acrylic counterparts. The specifically developed water soluble acrylic emulsion sealer used with this process has no known unusual fire or explosion hazards, it meets State and Federal VOC regulations, is biodegradable in accordance with ISO/DIN 8192:1986.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a diagram showing the typical paver installation depicting paver, sand joint, and base materials

FIG. 2 is a diagram depicting an existing paver installation with environmental degradation

FIG. 3 is diagram depicting an existing paver installation after power washing to remove environmental degradation that results in missing sand joint material

FIG. 4 is a diagram showing the paver installation and filling missing or damaged sand joints

FIG. 5 depicts the rinsing off of excess sand material from surface of the paver

FIG. 6 depicts the flood coat application of sealant

FIG. 7 is a diagram of the completed application, sealed paver and stabilized sand joint

To appreciate the invention described herein, one must examine the manner in which paver sealer chemicals are typically applied today.

Normally, pavers FIG. 1 (1) are set in a prepared base foundation suitable for the local soil, climatic and geographical conditions. In frost free areas this base foundation may only consist of a several inches of aggregate material base FIG. 1 (4), while in northern parts of the country exposed to severe frost the aggregate material base FIG. 1, (4), may be many inches thick and will probably contain drainage components to reduce the likelihood of frost heaves. Typically, an aggregate base FIG. 1, (4) or asphalt treated based is topped with bedding sand base FIG. 1 (3). Individual pavers FIG. 1, (1) are set in the bedding sand material FIG. 1 (3) and spaced to produce a small gap, typically ¼ inch, which is filled with sand or an equivalent material as shown in FIG. 1, (2), the sand joint. The inter-paver joints FIG. 1, (2) are usually filled by spreading the appropriate filler sand or equivalent material such as crushed or pulverized rock on the surface of the pavers and then sweeping the material into the paver joint FIG. 1, (2).

The typical method of application of sealers requires at a minimum multiple days to complete.

The multi-step process involves various steps as outlined below:

-   -   1. Prior to sealant application, existing paver surfaces FIG. 2,         (5) must be washed of any mold FIG. 2, (6), mildew FIG. 2, (7),         fungus FIG. 2, (8), tire marks FIG. 2, (9) and other surface         contaminants. A power washer is usually filled with soap and         city tap water usually containing small amounts of chlorine is         used to clean the paver surface.     -   2. After the cleaning step and removal of the environmental         degradation FIG. 3, (11), prior art sealing processes required         the pavers FIG. 1, (1) and joint sand FIG. 1, (2) to dry for         multiple days until completely dry.     -   3. As a result of the power washing and removing areas of         environmental degradation FIG. 3, (12) some joint sand may be         forced from the paver joints FIG. 3, (13), necessitating         sweeping additional joint sand into the paver joints. New         installations will always require the filling of the paver         joints. The prior art sealant application process typically         filled the paver joints by sweeping dry sand into the paver         joints after the pavers had dried. After the filling the paver         joints with sand any, loose sand must then be hosed, blown or         swept off of the pavers.     -   4. Usually after a multiple day drying period the sealant is         applied to the pavers and joint filler sand. In the past it was         very important that the pavers be completely dry prior to         sealant application. Application to completely dry pavers         minimized the likelihood of bubbling, foaming, and formation of         effervesce (Calcium Carbonate).

If the pavers were completely dry during the sealant application the application was usually successful resulting in a proper surface enhancement and seal. More often than not the finished product contains imperfections due to the presence of moisture or contaminants during the application of the sealant. This resulted in call backs where the applied sealer in many cases needed to be stripped and the process repeated. Call backs are a time consuming and costly activity.

Particularly troubling is the problem of moisture in the application of paver sealants. The ability of the installation labors and crews to determine the moisture content of the pavers prior to application of the sealant is difficult at best. A multitude of laboratory like tests can be used to determine moisture content and moisture transmission of the pavers. Such tests include: The Plastic Sheet Test, ASTM-D-4263, Calcium Chloride Test, Gravimetric Test, Electro-conductive test, litmus test and other tests not well suited to labor crews performing the actual work of applying the paver sealer. Further, complicating the task for the sealer contractor is the uncertainty of the weather and its impact on the efficient scheduling of the field crews work. The application of most paver sealants is prone to contamination from something as uncontrollable as moisture and this, further results in an unacceptable level of call backs.

It would therefore be an advance in the art if a process could be developed for an environmentally friendly sealant not subject to the same restrictions as prior art sealants. More specifically, a new environmentally friendly sealant used in conjunction with a novel sealing process that could be conducted in less time with fewer steps and be less susceptible to moisture, chemical and biological contamination.

BACKGROUND OF THE INVENTOR

The inventor of record for this process patent application is in the business of paver sealing and has used a number of sealing products and has followed the manufacturers directions in the application of those numerous products. The inventor through years of personal experience found that the application of available sealers to outdoor pavers could not assure the warranted final product performance with 100% certainty. The uncontrollability of the paver moisture content from one paver location to another on the same job site introduced uncertainty in the prior art application process. Furthermore, the inventor personally experienced the frustration of unexpected rain that either ruined an application currently underway or rain that resulted in a delay impacting subsequent job scheduling. Other problems associated with calcium carbonate further plagued the application of sealers. The inventor's personal experience allowed him to realize the need for a sealer and sealing process that was predicable with a high probability of success and capable of application under a variety of conditions.

The inventor not only realizing the need for such a sealer and application process took the inventive steps to work to develop the new sealant, to conceive the cost effective application process, and ultimately reduce the invention claimed herein to practice. The inventor within 35 U.S.C. 102 (b) statutory limitations has submitted this patent application.

The inventor's experiments resulted in numerous failed application attempts. The experiments involving various types of sealers resulted in failed sealer applications. Failures consisted of bubbling, foaming, white calcium carbonate resides and other visual imperfections. Further hindering the inventive process was the uncertainty of a uniform site moisture content and the uncontrollability of the weather. The inventor, frustrated with the inability to control the outcome of the paver sealing application with a high probability of success embarked on the inventive steps to: 1. work with a chemist to implement his ideas in developing an improved sealer; 2. invent a process for application that could assure that the final sealer product could be assured with a high probability; 3. to invent a process that minimized the formation of calcium carbonate and 4. to invent an application process that was economically attractive one capable of application under wet conditions with an assured high probability of success.

Numerous experiments were conducted. Various custom sealers were developed and ultimately applied under various environmental conditions. Dry and wet applications produced varying results using the various custom blended sealers. These experiments finally led to a water soluble, environmentally friendly acrylic emulsion sealer that could be applied in a manner that facilitated ease of application (economical installation); was immune to the problem of moisture content and the weather precipitation; and could be applied with a high probability of success under a wide range of environmental conditions.

After numerous successful applications of the custom developed acrylic emulsion sealer using the newly developed application process the inventor submitted this application for patent.

SUMMARY OF THE INVENTION

Having described the limitations of the prior art systems, the invention herein disclosed represents an advance in the sealing of paver surfaces. Such an advance results in a more environmentally friendly process that enhances paver surface finish, seals pavers against environmental degradation, stabilizes the inter paver sand joint and requires less time and fewer steps resulting in a more economical sealant application. Such an invention meets the requirements for novelty and usefulness, hence is suitable for patent protection.

The recently developed acrylic emulsion sealer was designed to be applied to the pavers after power washing; with no need for drying; a controlled viscosity allows for one day service. The invention described herein describes such a process to be used with the custom designed water soluble acrylic emulsion sealant.

The inventive application process described herein may be used to enhance, seal and protect existing paver installations or new paver installations. For existing paver installations the processes may consist of an initial washing and cleaning using for example a power washer or other cleaning appliance. FIG. 1 illustrates a typical existing paver installation showing the elements of the typical paver installation as described in above. The paver surface FIG. 2, (5) is the external surface that is exposed to environmental degradation as shown in FIG. 2, mold (6), mildew (7), fungus (8), and tire marks (9).

The physical pavers are composed of a white or gray cement, aggregates, sand and optional pigments used to color the pavers. Pavers are manufactured in the usual manner. A vitreous firing similar to ceramic tiles is usually not performed on exterior concrete pavers, since it is desirable to have a non-gloss, non-slip surface finish. Ceramic surfaced pavers are not usually sealed with this surface process.

The porous paver surface FIG. 2, (5) with the application of the water soluble acrylic emulsion sealant will experience a surface enhancement and sealing. The paver absorbs the applied acrylic emulsion sealant resulting in an increase in surface luster thus providing a more visually appealing paver surface. The sealer penetrates the surface of the paver and forms a bond with the internal capillary concrete structure of the paver.

The sand joint FIG. 1, (2) is the joint between adjacent pavers filled with a suitable sand or sand like fractured material. This joint requires stabilization so that the sand or sand like material does not erode from the joint during times of heavy rains or wind. The stabilization of the sand joint locks in place the individual grains of sand or sand like material through the establishment of a bond produced by the acrylic emulsion sealer. The stabilization not only bonds the individual grains of sand or sand like material to each other, but also bonds the individual gains of sand to the pavers.

Existing installations of paver surfaces FIG. 2, (5) may be environmentally degraded by mold FIG. 2 (6), mildew FIG. 2, (7), fuigus FIG. 2, (8), and tire marking FIG. 2, (9) and other physical damage such as sun FIG. 2 (10), and rain FIG. 2, (11). To remove the naturally occurring and man induced surface finish damage power washing is usually performed. Power washing and cleaning removes the environmental degradation FIG. 3, (12) and pealing or flaked surfaces of old sealers. The cleaning process typically removes surface sealant and degrades the surface finish, making the pavers look flat and unattractive necessitating the need for subsequent sealing.

In the event that sand joints are damaged by power washing any resulting missing sand joint material FIG. 3, (13) must be replaced by re-filling the joint FIG. 4, (14). Joint filling for new installations or those damaged by power washing is usually accomplished by manually spreading sand or a sand like material on the surface of the pavers and sweeping it into the joints. Excess sand FIG. 4, (15) is typically hosed off FIG. 5, (16) with a low pressure water rinse or by wet sweeping. As the water drains off the surface of the pavers into the joints, which further compacts the sand granules thus filling the joint. The porosity of the sand joint and the sand bedding material allow the water to quickly drain from the paver surface.

Normally, with other prior art sealant application processes, the application process stops at this stage. Prior art sealants require the sand and pavers be moisture free. This can result in days of delay prior to the final application of the prior art sealant. The inventive novel process described herein does not suffer from a similar delay.

The inventive process proceeds usually on the same day with the application of an environmentally friendly water soluble acrylic emulsion while the pavers and sand are still wet FIG. 6, (17) from the low pressure rinse water. A flood coat FIG. 6, (18) of the custom developed acrylic emulsion sealer is applied to the surface of the wet pavers. A flood coat is a heavy coating of sealant resulting in puddling of the sealant on the surface of the pavers. The custom developed acrylic emulsion sealant penetrates the surface of the pavers and the porous sand joint. The water based sealant is quickly absorbed by the porous surface of the paver and sand joint, hence providing a deep seal and sand joint stabilization. Multiple coats provide deeper penetration and enhanced surface luster and joint stabilization.

The reduction of effervescence is achieved since the water soluble acrylic emulsion sealant is applied wet using a flood coat. The deviation from other prior art processes now becomes apparent in this non-obvious novel application step.

Other prior art application processes that require an extended period of drying time provide an opportunity for the transmission of internal paver moisture and the ultimate transmission of calcium hydroxide Ca(OH)₂ from within the paver the surface of the paver. When the calcium hydroxide encounters carbon dioxide in the atmosphere the problematic white calcium carbonate CaCO₃ is formed.

Ca(OH)₂+CO₂>CaCO₃+H₂O

A sealer application over a calcium carbonate deposit can result in the white CaCO₃ residue and usually a call back. The novel application process using the acrylic emulsion sealant described herein overcomes this problem, since it reduces the time under which calcium carbonate can form.

The first action that reduces the formation of calcium carbonate is that the wet paver is not given sufficient time for high concentrations of calcium hydroxide to be carried from within the paver to the surface of the paver prior to the application of the acrylic emulsion sealant. The paver is not given the opportunity to dry, nor is atmospheric carbon dioxide given the opportunity to reach the surface of the paver, since the pavers are protected by a thin film of rinse water FIG. 6, (17). A flood coat of penetrating water soluble acrylic emulsion sealant FIG. 6, (18) is applied while the surface of the paver is still wet. The sealer's additional wetting action acts as a further barrier to atmospheric carbon dioxide reaching the paver surface.

The second reason calcium carbonate is not given the opportunity to form is that the necessary concentrations of calcium hydroxide on the paver surface are never allowed to form, thus suspending the formation of calcium carbonate effervesce usually encountered during the drying time of prior art sealing processes. As the calcium hydroxide attempts to percolate to the paver surface as part of the natural paver drying process, the penetrating water soluble acrylic emulsion penetrates into the paver.

As the water soluble sealant penetrates into the paver, it bonds with the concrete capillary structure of the paver. The sealer dries before the internal moisture in the paver is completely wicked to the surface. Since the sealer dries prior to the internal moisture being wicked to the paver surface, the paver surface is protected from effervescence. After the sealer dries paver internal water moisture slowly evaporates through the “pores” in the dried sealer. The controlled viscosity of the custom developed sealer assures that the pavers are properly sealed with a minimum of calcium carbonate formation.

To deter the growth of mold, fungus and mildew, a water-soluble fungicide may be added to the acrylic emulsion sealant affording additional protection from biological fungal attack. An additional additive may also be added to the acrylic emulsion sealant to retard the generation of black tire marks when pavers are to be used in parking areas.

The major advantages of this inventive application process is that no drying time is necessary prior to the application of the water soluble acrylic emulsion sealant formulated for this application process. A further advantage for this process over the prior art is that the problematic white residue and effervesce associated with solvent based sealants is eliminated since the application is performed while the pavers and sand joints are wet.

FIG. 7 depicts the finished application of acrylic emulsion sealant. The paver FIG. 7, (19) contains a protective surface film FIG. 7, (20). This protective film acts a seal to weather and other environmentally damaging external forces such as mold, mildew and fungus. The acrylic emulsion sealant penetrates into the porous concrete structure and bonds with the capillary structure of the concrete, thus slowing the migration to the surface of Ca(OH)₂ FIG. 7, (21) during the normal drying of wet pavers. The formation of calcium carbonate involving atmospheric carbon dioxide (CO₂) FIG. 7, (23) is slowed with the sealed paver surface FIG. 7, (20) where the seal acts as a barrier to its formation.

Sand joint stabilization is shown in the FIG. 7, (22) where the acrylic emulsion sealant penetrates down into the sand joint, locking the individual grains of sand together and bonding them to the paver surface. Sand joint stabilization results in a sand joint that will not blow out or wash out during times of high wind or heavy rains.

It is obvious that minor changes may be made in the process steps, form and construction of the invention without departing from the material sprit thereof. It is not, however to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed. 

1. A method for sealing pavers with a water soluble acrylic emulsion sealant where said method comprises: a. cleaning the surface of the pavers with a high pressure hydraulic process using a liquid selected from the group of liquids comprising water, and water soluble cleaning soap; b. filling paver joints with a material selected from the group of sand, gravel dust, powered rock; c. rinsing the pavers with a low pressure water wash; d. applying while the pavers are still wet a water soluble acrylic emulsion sealant to the surface of the pavers and sand joints in a flood coat and e. allowing the sealant to dry on the pavers and filled joints thus sealing the pavers and stabilizing the sand joints between pavers.
 2. A method for enhancing the surface finish of pavers with a water soluble acrylic emulsion sealant according to claim (1) where said method further comprises: a. applying a water soluble acrylic emulsion sealant containing at least one additive selected from the group of algaecide, fungicide, and non-tire marking additives to the surface of the pavers and joints in at least one flood coat.
 3. A method for sealing pavers with a water soluble acrylic emulsion sealant where said method comprises: a. filling paver joints by sweeping into the joint a material selected from the group of sand, gravel dust, powered rock; b. rinsing the pavers with a low pressure water wash to remove excess sand used in paver joint filling; c. applying while the pavers are still wet a water soluble acrylic emulsion sealant to the surface of the pavers and joints in a flood coat and e. allowing the sealant to dry on the pavers thus providing visual surface enhancement of the paver surface.
 4. A method for enhancing the surface finish of pavers with a water soluble acrylic emulsion sealant according to claim (3) where said method further comprises: a. applying a water soluble acrylic emulsion sealant containing at least one additive selected from the group of algaecide, fungicide, and non-tire marking additives to the surface of the pavers and joints in at least one flood coat. 